When President Obama signed the Affordable Care Act, its requirement that large employers provide health coverage or pay a penalty seemed to many supporters a key pillar of the effort to guarantee health coverage to Americans. Four years later and after repeated delays, the so-called employer mandate has become something of an orphan, reviled by the law's opponents and increasingly seen as unnecessary by many of its backers. Twice in the last two years, the Obama administration has put off the penalties, citing difficulties enforcing the mandate. House Republicans plan to sue the president, largely over his suspension of the mandate, saying he has broken the law by failing to enforce a requirement that they bitterly oppose.